Water distribution systems (WDSs) have become large, complex interconnected infrastructure elements that need computer tools for their management decision-making and design. An important need that usually arises in long-term planning is where an optimal reinforcement or design of the network is sought. The designer needs to decide which hydraulic device to add, what their settings should be and what should be the characteristics of the pipes. A number of formulations have been proposed in the literature to solve this problem. The most popular developments use meta-heuristic techniques to solve a nonlinear, mixed integer problem that minimizes the total cost with respect to hydraulic integrity and performance constraints. Global sensitivity methods can be used to screen out insensitive decision variables to reduce the computational demand associated with an optimal Pareto front construction. In this research, we explore a novel way to test the influence of the decision variables by introducing, in the pressure-driven, steady-state model, flow constraints qmin